16 Cold and Flu Myths You Need to Stop Believing

You can’t pass it on unless you have a fever

Just because you don’t have symptoms right away doesn’t mean that the virus is not in you. Most healthy adults may be able to infect other people beginning the day before their signs develop and up to 5 to 7 days after becoming sick, according to the CDC. Symptoms start 1 to 4 days after the virus enters the body. Between 20 and 30 percent of people with the flu virus don’t experience signs. Alarmingly, a study in England showed that 77 percent of flu infections have no symptoms.